Ski lift control mechanism



p 1968 E. F. KIRCHER 3,401,643

SKI LIFT CONTROL MECHANISM Filed Nov. 29, 1965 3 Sheets-Sheet 1 FIG. I

INVENTOR. EVERETT F. K( RQHER A'ITO re NEQS P 19.68 E. F. K IRCHER 3,

SKI LIFT CONTROL MECHANISM Filed Nov. 29, 1965 3 eets-Sheet 2 N 9' LL.

- INVENTOR. EVEKQH- KIRHEIL P 1968 E. F. KIRCHER 3,401,643

SKI LIFT CONTROL MECHANISM Filed Nov. 29, 1965 5 heets-Sheet 3 LP I J INVENTOR. EVERETT F KIRCHER ATTEDQ NEIVS United States Patent 3,401,643 SKI LIFT CONTROL MECHANISM Everett F. Kircher, Boyne Mountain Lodge, Boyne Falls, Mich. 49713 Filed Nov. 29, 1965, Ser. No. 510,217 4 Claims. (Cl. 104-173) ABSTRACT OF THE DISCLOSURE A safety control mechanism for a chair lift which is operably connected to the propulsion unit of the lift so as to halt movement of the chair should the same be tilted beyond a safe attitude. The safety control mechanism preferably includes switch arms mounted one on each side of the path of travel of the chair near the exit end of a pair of guides which keep the chair from tilting excessively during passenger loading or unloading. If the chair is improperly loaded so as to tilt it excessively when freed from the guides, the chair will actuate the arms so as to halt the chair before it has moved beyond the loading or unloading area.

This invention relates to aerial cable lifts, and more particularly to a safety control mechanism for a continuously operating chair lift of the type wherein each of the chairs is adapted to carry a plurality of persons.

Prior to the present invention, ski lifts equipped with chairs having a seat width adapted to accommodate two persons side-by-side have been in successful and relatively widespread use. More recently, a so-called tripple chair lift has been installed and operated with some degree of success. However, due to the increased width of the seat required to accommodate three persons side-byside, the tendency of the chair to tilt is markedly increased over that of the double chair and therefore increased supervision and operating personnel are required to insure safe loading and unloading of the three passenger chairs. This problem arises primarily from the lateral instability inherent in the single point suspension of the chairs from the aerial cable, a system which is almost universally preferred for reasons of its simplicity and economy. Until the present invention, it was thought that the triple chair lift represented the ultimate in multiplace chair lifts inasmuch as the instability problems attendant upon any further increase in the width of the chair, particularly in loading and unloading, were believed insurmountable.

For example, when a four place chair lift was first proposed, it was considered impractical due to the high degree of tilt possible when carrying an unbalanced load, such as only one skier sitting all the way to one side of the chair. The angle of tilt is proportional to the square of the distance measured from the center of gravity of the unbalanced load to the center post by which the seat is suspended from the overhead cable. Thus, the severity of the problem increases fourfold when the seat width is increased twofold. If a four place chair were allowed to leave the loading platform improperly loaded, the upper end of the chair suspension structure could be tilted sufiiciently to foul the cable or cause it to jump off the sheaves on which the cable runs and thereby derail the cable, which in turn could easily lead to a very serious 3,401,643 Patented Sept. 17, 1968 "ice or even fatal accident. Also, the tippiness of the four place chair presented a dangerous loading and unloading condition due to the difliculty in simultaneously seating four skiers on a moving chair, and the further difficulty of having them all disembark simultaneously from the chair at the top of the hill.

Accordingly, it is an object of the present invention to provide an improved chair lift construction, particularly adapted to be used as a ski lift, which embodies novel safety features enabling safe and successful operation of an extra wide chair, such as one adapted to seat four adult size passengers in comfort, thereby greatly increasing the capacity of existing ski lift equipment to the mutual benefit of the lift operator and skiers.

Other objects, features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a fragmentary terrain profile illustrating the downhill end of a chair lift constructed in accordance with the present invention and particularly adapted to be used by skiers.

FIG. 2 is a fragmentary perspective view on an enlarged scale of the downhill end of the ski lift, shown in simplified semi-schematic form, with a four place chair shown traveling over the loading platform.

FIG. 3 is a fragmentary perspective view looking in the direction of the arrow 3 of FIG. 2.

FIG. 4 is a fragmentary perspective view illustrating the operation of the safety switch mechanism of the invention as seen from beneath the mechanism.

A chair lift constructed in accordance with the present invention may be installed on substantially any type of terrain, such as that illustrated in profile in FIG. 1. The general arrangement of the ski lift is well understood in the art and may be somewhat similar to that shown in United States Patents 2,582,201, 2,938,472 and 3,115,847. As shown, the lift extends from a lower terminal 10 up the slope 12 to an upper terminal (not shown). A single endless cable 14 is trained at one end around a driving bull wheel 16 mounted at the upper end of an upright axle 18, the cable being trained at its uphill end around an idler bull wheel (not shown). A suitable prime mover, indicated schematically at 19 (FIGS. 1 and 2), such as an electric motor or electrically controlled internal combustion engine, is connected in a conventional manner to rotatably drive bull wheel 16 under the control of the safety mechanism of the invention as described hereinafter. The runs of cable 14 intermediate the terminal bull wheels are supported by sheaves 20 carried on towers 22 spaced along the length of the lift in the usual manner. A plurality of four place chairs of the present invention are suspended in a conventional manner at spaced intervals from cable 14, the single cable serving to both carry the chair and to propel the same along the route of the ski lift.

A suitable loading platform 26 (FIGS. 1 and 2) is disposed adjacent the downhill bull wheel 16 and extends beneath the path of travel of chairs 24 on the uphill run of cable 14 for a suitable distance to accommodate loading of passengers onto chairs 24 while the same are moving over the platform. Similarly, an unloading platform (not shown) is located beneath the uphill run adjacent the uphill idler bull wheel for discharge of the passengers from the chairs. Loading and unloading stations may also be provided for the downhill run of the cable for installations where the chair lift is used for transport of passengers both to and from the summit, as is common during the summertime to accommodate the sight-seeing tourist trade.

As best seen in FIGS. 2 and 3, the chair suspension structure includes a pair of hanger brackets 28 and 30 suitably fixed to cable 14 and extending laterally from the outboard side thereof. A pair of hanger bars 32 and 34 are pivotally connected at their upper ends one to each bracket for swinging motion in the direction of travel of cable 14. The lower ends of hanger bars 32 and 34 are similarly pivotally connected by spaced attachment plates 36 and 38 (FIG. 3) to the upper end of a center post 40 which in turn is rigidly connected at its lower end to a seat 42 and back 44 of chair 24. This pivotal suspension arrangement is designed to permit fore and aft sway of chair 24 in the manner of a parallelogram linkage so that seat 42 does not tilt relative to the loading platform 26 during fore and aft sway of the chair in the direction of cable travel. Such fore and aft sway of the chair is desirable to accommodate both loading and unloading of the same since it permits travel of the chair to be slowed and temporarily halted as the skiers seat themselves in the chair or disembark from the chair without halting motion of cable 14.

However, the chair suspension structure as thus described also permits lateral sway or swinging of the chair about cable 14 as an axis, even though brackets 28 and 30 are firmly clamped to the cable, due to the ability of the cable to twist. This lateral sway is a very serious problem which is greatly aggravated by the extra wide seats required to accommodate four adult size passengers on a single chair, for the reasons mentioned previously.

In accordance with the present invention, this lateral sway problem is overcome at the loading and unloading stations by a pair of guide rails 46 and 48 which are rigidly supported below cable 14 ,by horizontal cross members 49 connected to uprights 50 of the usual tower structure (not otherwise shown) associated with the downhill bull wheel 16. Guide rails 46 and 48 are arranged to extend parallel to the path of travel of hanger bars 32, 34, rail 46 being disposed on the inner side and rail 48 on the outer side of the travel path of the bars. Guide rails 46 and 48 preferably comprise angle iron material disposed with one flange 51 vertical and the other flange 52 extending horizontally away from the hanger bars. Preferably, rails 46 and 48 extend from a point along the downhill run of cable 14 around the outboard side of the bull wheel 16 and then along the uphill path of travel of bars 32 and 34 for a major portion of the length of loading the platform 26, terminating at ends 54 and 56 which are preferably located several feet short of the uphill end of I loading platform 26 and which are curved smoothly outwardly away from the path of travel of the hanger bars.

Guide rails 46 and 48 are spaced horizontally apart a predetermined distance sufiicient to allow hanger bars 32 and 34 to pass freely therebetween in the balanced condition of the chair 24 as shown in FIG. 3. However, if chair 24 becomes unbalanced during loading or unloading of passengers, thereby tending to tilt the seat laterally as permitted by cable twisting, the hanger bars will strike one or the other of the guide rails to thereby limit the maximum angle of tilt to within a safe range, for example, about 3 degrees. During such unbalanced condition, bars 32, 34 are permitted to slide along the face of flange 51 of the restraining guide rail. The chair will thus be restrained against excessive tilting during its traverse of a major portion of the length of the loading station 26, thereby allowing sufiicient time to seat a balanced load of up to four adult size passengers on the chair while maintaining the chair relatively steady.

If a particular chair has not been properly loaded by the time bars 32 and 34 arrive at the uphill exit ends 54 and56 of the guide rails, the outwardly curved ends 54 and 56 would permit progressively increased tilting of the chair as the hanger bars slid along the curved surface of which ever end is restraining the same. If the chair were permitted to proceed clear of the rails, the unbalanced load would cause the unrestrained chair to tilt laterally until it reached a stable, fully tilted position. Such a chair would constitute a hazard both to its occupants and other chairs on the lift due to the likelihood of jambing at the support sheaves 20 or the possibility of cable derailment due to the resultant tilt of the brackets 28 and 30 as they pass over the sheaves.

In accordance with another feature of the present invention, a safety mechanism is provided which insures that such an unbalanced, excessively tilted chair is not allowed to proceed on up the lift but rather is stopped while still disposed above the loading platform to permit immediate correctionof the unbalanced condition, as by reseating the passengers in a balanced arrangement or permitting the chair to be unloaded and proceed on its way in a balanced unloaded condition. A pair of safety switch arms 60 and 62 are respectively pivotally mounted on curved ends 54 and 56. The inner ends 64 and 66 of arms 60 and 62 respectively are spaced a predetermined distance from one another adjacent the path of travel of hanger bars 32 and 34 such that the hanger bars of a properly balanced chair will pass between ends 64 and 66 without striking the switch arms. However, if a chair is dangerously unbalanced as it leaves the guide rails, it will swing outwardly, for example, as shown in broken lines in FIG. 3, as it slides along the curved end 56 until it strikes the portion of switch arm 62 projecting inwardly from rail end 56 to thereby pivot inner end '66 in the direction of travel of bars 32, 34 and the outer end 68 in the opposite direction, thereby actuating a switch connection which is operable to cut off electrical power controlling or energizing the lift drive motor 19 and thus immediately stop the chair lift.

Although any of the well known trip arm switches may be used in the safety mechanism of the invention, the switch arrangement shown in FIG. 4 represents a simple yet highly practical form of safety switch of the invention. In this embodiment, switch arm 60 comprises a piece of steel strip stock pivotally mounted by a bolt 72 to the horizontal flange 52 of end 54 of guide rail 46 so as to rest on the upper surface of flange 52 and be guided for pivotal movement in a plane perpendicular to the path of travel of hanger bars 32 and 34. Inner end 68 of arm 60 has a cable or cord 74 secured at one end thereto, cord 74 having attached to its other end a standard two prong electrical plug 76 the terminal posts of which are wired together by a jumper wire so that the prongs 78 of the plug are in series with one another. Plug 76 when plugged into a standard mating socket 80, mounted on the rail, is adapted to complete the connection between the two leads of the electrical cord 82 connected to socket 80. The remote ends of the leads of cord 82 are connected in circuit with any suitable control mechanism for the lift drive motor such that when the circuit is completed by plug 76 in receptacle 80, the control is energized and the lift drive is on. When end 64 is struck by a hanger bar of an unbalanced chair, the outer end 68 pivots in the direction of the arrow shown in FIG. 4, thereby pulling plug 76 out of socket 80 and thus breaking the power control connection. With this arrangement the chance of switch failure is reduced to a minimum and the mechanism is fail safe in that any short or open circuit condition in lead 82 likewise will stop the lift drive.

From the foregoing description, it will now be apparent that the present invention provides a chair lift construction embodying a novel guide means and tilt sensing means which cooperate with any type of chair suspension having freedom to tilt laterally to insure that continuous operation of the lift occurs only when properly loaded or balanced chairs leave the loading station of the lift. The safety mechanism of the present invention thus makes it possible to employ extra wide chairs without fear of incurring undue risks due to their aggravated tendency to tilt when unbalanced, thereby resulting in the successful and safe operation of a four place chair lift, an operation hitherto thought impossible. This is accomplished by guide rail and switch structure of the utmost simplicity and hence at a minimum cost.

It is to be understood that it is within the scope of the present invention to utilize a safety device wherein the sensing element of the switch, e.g., arm 60 and/ or arm 62, comprises the trip arm of a toggle switch or other equivalent mechanical actuating arrangement. Alternatively, more sophisticated sensing elements, such as proximity switches or electric eye light beam sensors adapted to sense the tilted position of the chair suspension structure and actuate a motor shutoff device in response to the occurrence of an unbalanced load on the chair, may be substituted for the illustrated switch mechanism, although their additional complexity and cost renders them less desirable in most instances than the simple switch arm arrangement illustrated. Also, while it is preferred to locate the sensing switch just prior to departure of the chairs from the loading station so that the cause of an unbalanced chair may be conveniently and readily corrected by supervisory personnel at the lOading station, it is to be understood that similar tilt sensors may be located at other points along the path of travel of the cable, such as adjacent each supporting sheave, to further enhance the security and reliability of the lift. However as a practical matter, successful results have been achieved by the provision of the safety switch mechanism of the invention only at the loading station since the likelihood of a balanced chair becoming unbalanced at some other point is extremely small.

I claim:

1. A safety mechanism for a suspended chair passenger lift of the type having a chair including an upright member supported at its upper end by an Overhead cable and carrying a seat of the chair at its lower end and having drive means for moving the chair along the path of the cable, said safety mechanism comprising switch means adapted to be connected in controlling relation with said drive means whereby actuation of said switch means shuts off said drive means to halt operation of the chair lift, and sensing means operably connected to said switch means adapted to permit passage of the chair when suspended in a normal position with a balanced load and responsive to an abnormal position of the member I indicative of an unbalanced load on said chair to actuate said switch means, said switch means comprising a support adapted to be disposed adjacent the path of travel of the member, said sensing means comprising an arm mounted on said support for pivotal movement in the direction of travel of the member, said arm having a portion positioned to be clear of the member when the same is suspended in the normal upright position thereof but adapted to be struck by the member when tilted from the normal position, said arm being pivotable upon being so struck to thereby actuate said switch means, said switch means comprising an electrical connector having separable plug and socket members adapted when connected together to complete a motor energizing circuit of said switch means, and means connecting one of said connector members to said arm for movement therewith, the other of said connector members being affixed to said support whereby movement of said arm when struck by said member separates said connector members to thereby open said energizing circuit.

2. A suspended chair passenger lift including in combination aerial support means including an overhead cable, a chair having an upright support member connected at its upper end to said cable and having a seat carried by the lower end of said support member, electrically controlled drive means operable to move the chair along the pathof said cable, a passenger station extending beneath said cable, switch means connected in controlling relation with said drive means whereby actuation of said switch means shuts off said drive means to halt operation of the chair lift, sensing means adapted to permit passage of said chair when suspended in a normal position with a balanced load, said sensing means being responsive to an abnormal position of said member indicative of an unbalanced load on said chair to actuate said switch means, and guide means extending along the path of travel of said member above said station and disposed vertically between the paths of travel of the upper and lower ends of said member, said guide means having a trailing end positioned vertically above said station and between the entrance and exit ends thereof so as to be spaced from and in advance of the exit end of said station, said guide means being adapted to restrain movement of said member transversely of the path of travel thereof within predetermined limits to prevent excessive tilting of said chair during traverse of said stations, said sensing means being positioned adjacent the trailing end of said guide means relative to travel of the chair in a position to sense said support member when tilted beyond said predetermined limits whereby actuation of said switch means by said sensing means is effective to halt travel of said chair when carrying an unbalanced load thereon in the vicinity of the trailing end of said guide means and prior to the chair completing traverse of said station.

3. The combination set forth in claim 2 wherein said guide means comprises first and second stationary guide rails disposed one on each side of the path of travel of said member and spaced apart from one another to define said limits of maximum tilting angle of said member as it travels along and between said rails, each of said rails hving a trailing end curved outwardly away from the path of travel of said member, said sensing means comprising first and second arms movably mounted on said curved ends of first and second rails respectively, said arms being spaced apart to clear the path of travel of said member when said member is in said normal position thereof but disposed in the path of said member when titled to an abnormal position toward the rail associated with each said arm, each of said arms being adapted to move when struck by said member to actuate said switch means.

4. A safety mechanism for a suspended chair passenger lift of the type having a chair including an upright member supported at its upper end by an overhead cable and carrying a seat of the chair at its lower end and having drive means for moving the chair along the path of the cable, said lift having a passenger station extending beneath the cable, said safety mechanism comprising switch means adapted to be connected in controlling relation with the drive means whereby actuation of said switch means shuts off the drive means to halt operation of the chair lift, sensing means operably connected to said switch means adapted to permit passage of the chair when suspended in a normal position with a balanced load and responsive to an abnormal position of the member indicative of an unbalanced load on said chair to actuate said switch means, guide means adapted to extend along the path of travel of the member above the station and vertically between the paths of travel of the upper and lower ends of the member, said guide means being adapted to restrain tilting movement of the member transversely of the path of travel thereof within predetermined limits to prevent excessive tilting of the chair during traverse of the station, said sensing means being positioned adjacent the trailing end of said guide means relative to travel of the chair in a position to sense the member when tilted beyond said predetermined limits, said guide means comprising first and second stationary guide rails adapted to be disposed one on each side of the path of travel of the member and spaced apart from one another to define said limits of maximum tilting angle of the member as it travels along and between said rails, each of said rails having a trailing end curved outwardly away from the path of travel of the member, said sensing means comprising first and second arms movably mounted on said curved ends of first and second rails respectively, said arms being spaced apart to clear the path of travel of the member when the member is in the normal position thereof but being disposed in the path of the member when tilted to an abnormal position toward the rail associated with each said arm, each of said arms being adapted to move when struck by the member to actuate said switch means.

References Cited UNITED STATES PATENTS 2,938,472 5/1960 Tilgel 104173 5 3,115,847 12/1963 Turner 104-173 X FOREIGN PATENTS 162,076 1/1949 Austria.

1 ARTHUR L. LA POINT, Primary Examiner.

D. F. WORTH, Assistant Examiner. 

